I have been brewing drip Coffee on different devices. Kalita and Chemex mostly. Although the results have often been great. The biggest turn-off for me is getting an earthy, not-clean and bright tasting cup. I only use fresh specialty coffees so the problem cannot lie there. Any ideas?
The Kalita and Chemex equipment are designed for pour-over brewing. If you are using them as vessel-recipients of water from an automated dripper, it will not produce the kind of cup you desire due to the randomness at which it applies water over the bed of coffee.
If you are doing pour-over, there are a few major parameters that you will have to control to produce clean cups. Note that you will require a gooseneck kettle in order to have proper control over the water flow.
Grind. Ensure that you are using a burr grinder that is of decent quality, meaning that it can grind to a good consistency with a low number of fines. Fines are smaller granules of coffee produced in the grinding process as the beans are crushed and can over-extract to bring out bitter flavours. Your grind size should also be of medium level.
Water Temperature. This is one of the most important factors of the bunch for pour-over brewing in my experience. It's the parameter that you will change to fine tune how many compounds are being dissolved as you brew once you have a grind size that is in the right ball park. You should experiment with this as it will depend on the grind size and dose you use but I like to keep it at around 90 degrees Celsius.
Agitation. This measures how much you move and disturb the coffee. The more you agitate it by pouring, the more you continuously expose the coffee grounds to the water and encourage extraction. Controlling this will be another experimental variable for your specific parameters.
Aside from the above three that I believe to be the most important factors in what makes a clean pour-over brew, you should also take into account, the brew time, coffee-to-water ratio, coffee dose and obviously coffee origin and freshness.
First I think we really need to establish what exactly you mean with murky, unclean, earthy and bright cup and flavor. These are all quite different things and while unclean, earthy and murky are definitely not things you want in your coffee, brightness is usually a desirable attribute.
A clean cup of of coffee is characterized by the absence of unwanted flavors, that often result from defects in the beans (which would correspond to your earthy description). A lot of people though incorrectly use it to describe the absence of fines in your cup (which would be the murky part). So in this sense a cleaner cup than what you get with a Chemex is almost impossible. Thus I guess you are actually talking about earthy flavors, which are in fact defects. Those flavors you will most likely not get out of your coffee, since they arise not due to a wrong extraction. Your extraction might be perfect, but because of defective beans it will still taste earthy. These flavors are common in badly processed coffees (dried on actual dirt or mold during the drying process for example). However a balanced extraction might minimize the presence of these flavors in the profile, since other flavors might be more dominant.
Brightness is as I've said usually a desirable attribute in coffee, it refers to a nice, fresh flavor and acidity. So I'm not quite sure what you mean with it, maybe you could clarify on that point.
If you indeed talk about acidity then I guess your coffee could be underextracted (more info on how you extract would be helpful as well) or the roast is underdeveloped. Underdevelopment could also bring some grassy, herbal like flavors in your coffee that might be mistaken for earthy flavors.
In either case it seems to be the coffee and not your extraction, but without more info it's difficult to say.